Table 1.

Summary of included studies and extubation success based on cough peak expiratory flow thresholds

Authors/year	Extubation results	CPEF, mean (L/min)	CPEF threshold established (L/min)	Predictive power
Bach et al. 1996 [13]	43/58 success 15/58 failure	278.0 101.0	160.0	N/A
Smina et al. 2003 [17]	102/115 success 13/115 failure	81.9 64.2	60.0	Extubation failure RR 5.1 (95% CI 1.7–15.4)
Salam et al. 2004 [18]	74/88 success 14/88 failure	79.7 58.1	60.0	Extubation failure RR 4.8 (95% CI 1.4–16.2)
Beuret et al. 2009 [19]	116/130 success 14/130 failure	63.6 36.3	35.0	Extubation failure RR 6.9 (95% CI 2–24)
Su et al. 2010 [22]	118/150 success 32/150 failure	74.0 42.0	58.5	Extubation success RR 0.95 (95% CI 0.93–0.98)
Smailes et al. 2013 [20]	10/125 success 17/125 failure	125.8 74.2	60.0	Extubation failure RR 9.1 (95% CI 4–20.6)
Duan et al. 2014 [23]	95/115 success 20/115 failure	81.3 51.3	62.4	Predicting re-intubation Sensitivity 85.0% Specificity 64.2%
Kutchak et al. 2015 [21]	90/135 success 45/135 failure	115.3 75.8	80.0	Extubation success RR 0.64 (95% CI 0.51–0.83)
Duan et al. 2015 [16]	158/186 success 28/186 failure	74.3 51.7	Semiquantitative cough strength score (SCSS) SCSS 5 (113.7 L/min) SCSS 4 (79.0 L/min) SCSS 3 (57.5 L/min) SCSS 2 (44.7 L/min) SCSS 1 (39.5 L/min) SCSS 0 (38.4 L/min)	Extubation failure RR 1.0 (reference) RR 3.2 (95% CI 0.7–15.7) RR 4.0 (95% CI 0.8–19.1) RR 4.7 (95% CI 1.0–22.0) RR 6.1 (95% CI 1.3–29.0) RR 7.2 (95% CI 1.5–33.8)